System for energizing the electrodes of cathode-ray devices from the deflecting circuit



June 3, 1947. W J POCH 2,421,520

SYSTEM FOR ENERGIZING THE ELECTRODES 0F GATHODE RAY DEVICES FROM THEDEFLECTING CIRCUIT wg/wm.

T TOPNE )u/ 2,421,520 THODE W. J. POCH June 3, 1947.

SYSTEM FOR ENERGIZING THE ELECTRODES OF CA RAY DEVICES FROM THEDEFLECTING CIRCUIT Filed June 18, 1943 2 Sheets-Sheet 2 4BY v PatentedJune 3, 1947 imitan star ingr rr Fries Waldemar 3. Poeh, Moorestown, N.J., assigner to Radio Corporation of America, a corporation of DelawareAppiication June 1S, i943, Serial No. 491,332

This invention is directed to electronic apparatus and particularly totelevision apparatus of the electronic variety.

Most television apparatus incorporates a scanning or camera tube ofwhich there are many and various types. For purposes of illustration,this invention will be related to a scanning or camera tube or" theso-.called storage type such, for example, as that type which is nowcommonly known in the art as the iconoscope In many televisioninstallations where particular emphasis is given to the lightness ofweight the transportability of such equipment, it is frequentlydesirable to rely upon a common source oi energy for developing both thenecessary high voltage ior operating the system, as well as fordeveloping the heater current for the cathode electron emitters. Usuallythe heater current is an alternating current of low frequency serving toheat the electron emitters so that a stream or flow of electrons isreleased to form the electron scanning beam or cathode ray. It isusually desirable that there be some established frequency relationshipbetween the sources used to produce the high voltage energy and todevelop the heater currents, in order that greater eciency i operationshall be had, and such a relationship is had by this invention. Thevestablished relationship prevents any possible cross-talk eiects fromresulting in any noticeable picture ripple.

At the same time, this invention makes provision so that the usuallyconsidered separate heater current supply source becomes unnecessary,and the heater currents themselves are derived from one of the energydeections sources which, of themselves, serve to control, in knownmanner,

5 Claims. (Cl. 315-22) the motion or traverse of the scanning cathoderay beam across a target or mosaic element to produce a signalrepresentative of an optical image which has been cast upon this targetor mosaic.

In most embodiments of television systems where unilateral scanning isrelied upon, the scanning electron beam developed within the tube iscontrolled in its deection under the influence of deiiection energy ofsubstantially saw-tooth wave formation. Accordingly, in the presentinvention, the control energy from which .the operating voltages forproducing the relatively high voltage, aswell as for producing theheater currents, are developed and controlled under the iniiuence of theproduced delecting wave energy.

To this end, various means have been provided for producing a controlwave from which the energy is adequate to provide the heater current.

At the same time, this invention makes vprovision for developing thehigher voltages by .Way of a suitable high voltage rectier element whichis energized by a control Wave representing, for instance, a back-kickvoltage developed during the snap-back or return-trace portion of eachscanningI The invention herein to be disclosed also makes provision forproviding various ways and means by which the aforesaid results may beobtained, and, at the same time, provides ways and means by which thevarious relationships between the high voltage energy and the heatercurrents developed may be established.

It accordingly becomes one of the objects of this invention Yto providea television system having included therein a scanning instrumentalityin which a scanning beam is developed to scan an area, and in which thebeam not only can be controlled in a suitable manner in its deflection,but also suitable provision may be made whereby certain portions of theenergy of the controlling wave may be utilized todevelop the voltages bywhich the scanning beam is formed, and, at the same time, to provide theheater current energy source which causes the initial release of theelectrons to make up the scanning beam.

Other objects of the invention are those of providing a power supplysystem for a television or cathode ray device wherein the operatingvoltages are developed from a self-contained. unit, and wherein separatesources for developing the high voltages and the heater currents areavoided.

Other objects and advantages of the invention are those of providingways and means by which previously existing defects in prior art systemsare overcome and, at the same time, a power supply system is developedin which there is a great simplification .of the existing parts and agreater eiliciency of operating `than heretofore obtained.

Other objects and advantages of the invention wlil become apparent tothose skilled in the art to which the invention is directed when thefollowing speciications are considered in connection with theaccompanying drawings, wherein,

Fig. 1 represents schematically one form of system in which the featuresof the invention are incorporated;

Fig. 2 represents a modication of a portion of the circuit of Fig. l;and,

Fig. 3 represents still further modication of the arrangements of Figs.1 and 2.

Now making reference to the drawings for a further understanding of theinvention. it will be assumed, for the purpose of these considerations,that an electron tube of the cathode ray type (not shown) is providedwith suitable deilecting electrode means to which currents or voltagesof saw-tooth wave formation are applied, and the saw-tooth waveformation acting upon the deflecting electrode means causes thedeveloped cathode ray or scanning beam to traverse a target area of thecathode ray tube according to a desired pattern of scanning.

The wave form of the voltage or current developed and applied to thedefiecting electrode means (not shown) is of the general wave shapecomprising a saw-tooth wave portion and an impulse wave portion,somewhat like the wave forms shown by (b) on Fig. l. Accordingly, duringthe impulse section of such a wave, the impulse effects may betransmitted in a wave formation, illustrated by way of example as thewave form (a) on Fig. l, to an input terminal point Il, from which it isfed across the resistor element i3 and through the coupling condenser l5to the grid or control electrode l1 of an amplifier tube 25. Thisamplier tube 2] is illustrated, for example, Vas being of the form of adouble triode, although it is obvious that two separate tubes may beutilized where desired. However, for purposes of illustration, a tube ofthe general type, known in the art as the 12SL7GT, has been found to besuitable and is referred to by way of example.

The input energy of pulse wave formation, as shown adjacent to terminalpoint Il, is, as above stated, applied to the control electrode or gridi1 of the first half of the tube 25, of which the cathode element i9connects directly to ground 25, and a grid-leak to ground to providebias is connected in the form of the resistor 2l between the grid orcontrol electrode I7 and the cathode.

Also, for purposes later to be explained, blanking pulses (which do notdirectly affect the production of the heater current) for control areapplied at the second input terminal 23 and fed through the resistor 2land capacitor 29 to the grid or control electrode 3l of the second halfof the tube 20. At the point 28, constituting the junction of one end ofthe resistor I3 and the resistor 21, the line impulses fed to theterminal Il are miXed with the Vertical blanking pulses applied to theterminal 23. These two .pulses then serve to control both deflection and(if desired) blanking in the scanning or camera tube (not shown)although the rst half of the tube serves as that section of the tubeused mainly in connection with the power supply constituting primarilythe invention herein to be claimed.

At this point, however, it should be noted that the Second half of thetube 2i) also has its cathode element 33 preferably connected to ground25, and the resistor element 34 is connected in the same manner as thegrid resistor 2! of the iirst half of the tube.

When impulses are applied to the first half of the tube 25, it can beseen that with the cathode I9 connected directly to ground, nodegeneration takes place within the first half of the tube 20, and theimpulses are amplified in suitable manner. The amplied impulses are fedfrom the plate or anode 36 of the tube 20 by way of conductor 31 to thecontrol electrode 39 of the amplier 5G. These energy pulses are fedacross the resistor il and the serially arranged condenser 43 so that,at the junction point 44, a voltage pulse comprising the saw-toothsection and the impulse section is developed where, it will be seen, asubstantial portion of the voltage wave is below the 4 reference line,so that when the impulse section of the wave-form (b) is fed to the gridor control electrode 39 of the tube 40 by way of the coupling condenserM5, a substantial amount of energy is supplied in order that the currentfor operating the heater elements of the television or cathode ray tube,later to be described, will be available.

The ampliiier tube 40 has its cathode biased to ground 25 by way of thecathode resistor 4l, which is shunted by a condenser s to by-pass anyhigh frequency components. The grid bias for the tube is provided by wayof the resistor 5l connected between the grid or control electrode 39and ground 25.

For purposes of these considerations, it may be assumed that the plateor anode 53 of the tube iii), as well as the plate or anode elements 55of the first half of tube Eil, and 58 of the second half of tube 2b, areheld positive relative to the cathode elements by means of a voltageapplied at the terminal point 55 relative to the cathode elements of thetubes. In this connection it will be seen that the plate or anode 53 oftube 0 is held positive relative to its cathode 54 by the voltage fromthe source 55 (not shown in detail) being applied to the plate or anode53 through the primary winding 51 of an Voutput transformer 5S havingsecondary windings 59 and El, respectively.

When the voltage wave shown adjacent to the point 44 is applied acrossthe load resistor 55 for the rst half of tube 2) to the input of thetube dil, it produces, through the auto-transformer section 51-59 arelatively high voltage which is applied by way of a coupling condenser63 to the plate element 65 of a rectifier element 5l', having itscathode 69 grounded at 25. Under these circumstances, the tube 61functions in a manner somewhat similar to a grid-leak detector.

It will be seen that a rather large positive pulse is developed acrossthe resistor 'il due to the large positive pulse applied by way oftransformer section 5S with the Voltage wave form as appearing at pointd applied to control the tube d5. This voltage also appears across`thetube 6l so that a negative D. C. potential appears at the plate element55. The tube 51 has its plate or anode 65 connected to ground throughcondenser 13. The load resistor 'H and capacitor 'i3 together form alter which will remove all effects of the line pulses.

Under these circumstances there is developed, at the point i5, anegative potential relative to ground when the tube 61 draws current, sothat a relatively high voltage bleeder resistor, shown as comprising theresistor sections 75, 16 and 11, connects between the point 'I8 andground 25, so that the high voltage bleeder is connected in parallelwith capacitor 'i3 as the filter.

In this way it can be seen that the potential at point 18, which istransferred to a terminal point Bil by way of resistor 8|, is negativerelative to ground, and it may be assumed, for purposes of theseconsiderations, that the bias applied to the control electrode elementof the cathode ray type camera tube (not shown) is established by aconnection made at the point 85.

A connection to the cathode element of the same cathode ray or cameratube is made from point 82 and some intermediate point, such as 83, onthe bleeder resistor combination, and the rst anode element (not shown)of the same cathode ray or camera tube (not shown) may be assumed toconnect at point S4, which is tapped to the bleeder resistor at point85, which is substantially more positivev than the cathode connecting atpoint 83 and yet negative relative to ground 25. The second anode (notshown) of the same cathode ra-y tube Will be assumed, for purposes ofthese considerations, to operate as the most positive element of thesystem and, consequently, it will be connected in any suitable manner(not shown )l directly to ground.

From what has been stated above, it will be apparent that rectifier 61derives operating voltage in accordance with the output of the tube 40,which is controlled by a control voltage of saw-tooth and impulse waveformation', and that when this voltage wave is rectiiied by the halfwaverectier 61 and suitably smoothed by the lte'r combination, includingresistor 1| andL con"- denser 13, of which the latter' is ratherlarge'as a general rule, suitable high voltage operation of theV tube ismade possible.

At theY same time, the output voltage from the tube 48, as it appears inthe primary winding 51 of the auto-transformer 58, is applied to thesecondary winding 6|, as above noted, and this transferred voltage isthen of a frequencywhich is directly related to the frequency of thepulses applied at the input terminal l. In this way, at the. outputterminals 86 and 88 which connect by conductors 89 and 9| to the outerterminals of the secondary winding 6|, Suitable heater current for theheater element of the cathode ray or camera tube (both not shown) isdeveloped. Where desired, the inductance element 93 may be included inthe heater element leads in order to obtain the eiTects of greatersecond anode voltage for the tube and less heater current.

1 At the same time, since it was pointed out above that blanking on boththe horizontal return-trace and the vertical return-trace is essential,provision is made for feeding a part of the output of the second half ofthe tube by way of conductors 9d and 95 through the condenser 96 to theterminal point 8D, so that the blanking impulse may be applied at eachSnap-back or pulse period of the deecting wave energy at the terminalpoint 89. In this connection, it should be noted that it is preferableto arrange the time constant of the resistor 8| and the capacitor 95 sothat the hold period is approximately equalto the field frequencyrepetition rate, which, according to present R. M, A. practice, wouldbeof the order of 1/60 second.

Y Now, referring to the modifications of Fig. 2, it will be seen thatthe output voltage from the tube 40 (only a portion of the circuits arecompleted for simplication reasons) is supplied to the auto-transformersections 57 and 59 (of which the latter constitutes the secondarywinding) in the same manner as described in connection with Fig. 1.However, in contrast to the arrangement of Fig. 1, there are two furthersecondary windings, namely, the winding 6| from which the output voltageis fed to the terminal points 86 and 88 to supply heater current for thecathode ray tube (not shown), and also the winding 98 which has itsoutput terminals connected to the deecting coil elements 99 and |00,which are conventionally represented. These deecting coils may or maynot have the condenser |0| connected in shunt.

In the circuit modification shown by Fig. 2, it is apparent that thetube 40 is controlled from the pulses, such as those applied at terminalinput point and the saw-tooth voltage Wave formation which appeared atpoint 44 in Fig. 1 is then caused to be transferred directly to thedeflecting coils to force a saw-tooth current wave therethrough, incontrast to the separate input energy pulses hereinabove'explained inconnection with Fig. l. The output voltage from the secondary winding 69from the auto-transformer 58 is supplied', as in the arrangement of Fig.1, through the capacitor 63 to the high voltage rectifier 67 (not shownin Fig. 2).

In the modification of Fig. 3, provision has been made for utilizing aseparater oscillator which is synchronized from the horizontal or linedeflection frequency pulses which are shown and ap- Dlie'dto inputvterminal in Fig. 1. The heater and` anodeA operating voltages for thecathode rayy scanning or camera tube are then derived from thisoscillator. The voltage pulses, which appear at the point 44 in Fig. 1,are` applied by way of the condenser t9' at the input or controlelectrode|03 of an oscillator tube I D5.

The oscillator tube has its cathode |07 grounded by a direct connectionto ground at 25, and its grid condenser |89 is. provided With a gridleak resistor also connecting between the grid control electro'de |113and ground. The anode H3 of this oscillator tube has connected in serieswith the terminal point 55, from which the tube operating voltage issupplied, a tunedV resonant circuit H5 comprising the primary winding||1 of a transformer element IIS and a variable condenser element 2|connected in parallel with the transformer to tune the primary Windingto a predetermined frequency. Feed-back energy from the plate ||3 to thegrid |03 is provided by way of the' secondary winding |23, which has oneterminal connected to ground 25 and the other tei-- minal connectedv by|25 to feed back energy to plate l 3` to the control plate of grid 83 tosustain oscillations.

In the connection shown, heater current is now supplied to the terminalpoints 88 and 88 by way of the additional secondary winding 6| (as eX-plained for Figs. l and 2).

The high voltage for controlling the rectier 6l is supplied from theconnection point |21 by way of conductor |29 and the condenser 63 to thehigh voltage rectifier (not shown) but similar to the recti'er |51 ofFig. 1.

From what has been described above, it becomes apparent that' many andvarious modifications4 of thesystem herein set forth and disclosed maybe relied upon to produce the desiredheating currents and high operatingvoltages, and that these same currents and voltages may be developed andproduced completely in accordance with the deflection voltages used fordeflecting the cathode ray scanning beam developed in the apparatuswhich is to be controlled. Accordingly, it becomes apparent that manyand various modications may be made and utilized in accordance With theteachings of the invention as set forth.

Having described the invention, what is claimed 1s:

1. In television apparatus wherein is included a camera tube having atarget and means to develop an electron beam in combination With meansto cause the developed beam to scan the target, electrical wavegenerating means for producing electrical waves for controlling thedeection of the electron beam relative to the target area, transformermeans adapted to be energized by the output deflection controllingelectrical Waves from the generator, means for developing alternatingcurrent energy from the said transformer output to provide heatingcurrent for the electron beam developing means, and rectier means alsoadapted to be energized from the transformerA output for developingrelatively high voltage direct current output for energizing otherelectrodes of the electron beam developing means.

2. In television apparatus wherein is included a camera tube having atarget and means to develop an electron beam in combination with meansto cause the developed beam to scan the target, electrical saw-toothwave generating means for producing electrical waves having an impulseand a saw-tooth component for controlling the deiiection of the electronbeam relative to the target area, transformer means adapted to respondto the impulse component of the said electrical saw-tooth waves of theoutput of said generator, and means for developing from the saidtransformer output alternating current energy of a frequency related tothe frequency of the impulse components to provide heating current forthe electron beam developing means.

3. In television apparatus wherein is included a camera tube having atarget and means to develop an electron beam in combination with meansto cause the developed beam to scan the target, electrical saw-toothwave generating means for producing electrical waves having an impulseand a saw-tooth component for controlling the deflection of the electronbeam relative to the target area, transformer means connected to receivesaid generating means output and adapted to respond to the impulsecomponent of the said electrical saw-tooth waves, means for developingfrom the said transformer output alternating current energy of afrequency related to the frequency of the impulse components to provideheating current for the electron beam developing means, and rectifiermeans also adapted to be energized from the transformer output fordeveloping relatively high voltage direct current output for energizingother electrodes of the electron beam developing means.

4. In television apparatus wherein a cathode ray tube is used forvscanning and wherein the said cathode ray tube has an indirectly heatedcathode for emitting electrons and direct current energized acceleratingelectrodes for forming the electrons into a beam and for directing thesaid beam to a target electrode, means for developing electrical voltagewaves ofpredeterrnined wave-form for controlling the deflection of thedeveloped cathode ray beam across the target electrode according to apredetermined pattern of deflection,

transformer means adapted to have the primary winding thereof energizedby said voltage waves, rectifier means adapted to be energized by theoutput energy of the transformer secondary winding for developing arelatively high unidirectional voltage output controlled from the beamdeecting energy, and means 'for developing directly from the transformersecondary alternating current energy of a frequency coincidingsubstantially with the frequency of the developed deflecting voltagewaves and adapted to be used for heating the cathode element, wherebycross talk and scanning ripple eiects are substantially eliminated.

5. In television apparatus wherein is included a cathode ray scanningtube having a target area adapted to be traversed by a scanning cathoderay beam and wherein the cathode ray beam is developed from anindirectly heated source releasing electrons which are accelerated andformed into a beam under the influence of relatively highuni-directional voltages, means to generate sawtooth beam deiiectingvoltage waves for controlling the deflection of the developed cathoderay beam for each deflection cycle relatively slowly in one directionand rapidly returning it subsequently substantially to its initialposition, transformer means connected to have the input thereofenergized by the saw-tooth voltage waves, direct connections from thetransformer output for deriving alternating current energy adapted to besupplied to the heater elements from which the cathode ray beam isdeveloped, and means controlled by the current iiow in the transformermeans for simultaneously developing uni-directional acceleratingvoltages from the said saw-tooth deflecting voltage waves, whereby crosstalk and scanning ripple effects in the scanning pattern are eliminated.

WALDEMAR J. POCH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,962,873 Parker June 12, 19342,051,372 Farnsworth Aug. 18, 1936 2,074,495 Vance Mar. 23, 19372,262,630 Bahring Nov. 11, 1941 2,265,620 Bahring Dec. 9, 1941

